The present invention is directed to water temperature regulation, and in particular to controllable mixing valves and associated control for water temperature regulation for appliance usage.
In the consumer and commercial appliance industry, and with particular applicability to clothes washing machines, water temperature regulation is accomplished primarily through the timed mixing of hot and cold water inputs. The hot water input is typically provided from a consumer or commercial hot water heater which supplies hot water for various uses throughout the home or establishment. Depending on its other utilizations, the hot water is typically provided at a temperature of approximately 140xc2x0 Fahrenheit, although this temperature may be set by the user. The cold water input is typically provided at the tap from the cold water input into the home or establishment. While this cold water input is not typically temperature adjustable, common cold water inputs are approximately 60xc2x0 F. However, this temperature may vary depending upon location, installation, utility supply, etc.
While the hot and cold water are typically supplied at the above-described temperatures, seldom is the use for water at these particular temperatures. That is, most usages of the water require mixing of the hot and cold water inputs to accommodate a particular usage. For example, commercial and consumer clothes washers provide different washing cycles with user selectable water temperatures from hot, to warm, to cold. However, water at 140xc2x0 F. may damage some fabrics. Further, stringent consumer energy standards for these appliances limit the amount of hot water that may be used therein. Further, while cold water detergents are available and are in wide usage, particular for brightly colored fabrics, these detergents do not perform particularly well as the water temperature drops below, for example, 70xc2x0 F. As such, even clothes washing machines that provide hot and cold washing cycles do not typically utilize only water from either the hot or the cold input directly.
In such clothes washing machines, electronically controlled temperature mixing valves are typically employed to provide a combination flow of hot and cold water inputs to the washing drum. The control of the individual hot and cold water inputs to the mixing valve traditionally has been provided by an electromechanical timer circuit, although more modern controllers may replace the electromechanical timer function with an electronic timer control circuit. In either event, the operation of these two timing mechanisms is effectively the same from the mixing valve standpoint. As an example, the timer circuit may operate to provide a one-minute fill time of the washing tub. During that one-minute fill time, the timer may energize the electrically controlled valve for the hot water input to allow a flow of the hot water into the washing tub from the beginning of the fill cycle. The timer circuit may then energize the cold water input control valve after, for example, approximately 30 seconds of the fill cycle. In this way, the temperature of the water in the washing tub is reduced below that which would result if only the hot water valve were used. Different operating fill timing schemes are typically employed by the timer circuits to control the time during which each of the hot and cold water inputs are energized to provide the various water temperature cycles allowed by the washing machine.
While the timer control of both the hot and cold water inputs to the mixing valve operates satisfactorily for a majority of applications, various factors may exist in particular installations that do not provide satisfactory results for that particular installation. These problems relate to a breakdown of the primary assumption under which a timer controller may be utilized for temperature control of the water in the washing tub. Specifically, the timer relationships of a period of time for which each of the hot and cold water inputs allow the flow of their respective temperature water is based upon a generalized assumption of what the hot water temperatures and cold water temperatures are. However, in installations where the washing machine is remotely located from the hot water heater, for example, the temperature of the hot water input may initially be quite a bit lower than the typically assumed temperature of the hot water input.
As such, allowing the hot water valve to be opened for only a pre-selected period of time before the cold water valve is opened may result in a washing tub water temperature significantly below that which is desired and which would have resulted had the hot water input to the mixing valve been at its assumed temperature. In other words, if the temperature of the hot water input is only 120xc2x0 F. for the first 30 seconds of the fill cycle as controlled by the timer, opening the cold water input and closing the hot water input for the second half of the fill cycle will result in the water temperature of the washing tub being cool instead of warm as would have been the case if the hot water input were actually at its assumed 140xc2x0 F. temperature during the first 30 seconds of the exemplary one minute fill cycle.
Similarly, the temperature of the cold water input is likely to be higher than the steady state water input from the utility during the initial period of water flow, until the water in the pipe between the utility input and the washing machine is used up. This results from the ambient heating of the pipe and water when no water is flowing. As such, utilizing timed fill cycle control may well result in the washtub water temperature being much warmer than desired for a cold water wash where the hot water control valve is turned on for some timed period during the fill cycle time. Each of these problems is exacerbated by physical location of the washing machine in each particular location in relation to the utility cold water input and the location of the hot water heater, as well as the user temperature setting of the hot water heater itself.
Recognizing the problem that reliance on assumed water temperatures with a timer circuit presented, systems were developed to operate in conjunction with the water valve timer control to add an element of temperature sensing. One such system is described in U.S. Pat. No. 5,984,194 to Francalanci, entitled xe2x80x9cValve for Controlling the Temperature of the Water in a Washing Machine or Dishwasher, Methods of Treating Water in These Machines Which Can be Implemented by Means of Said Valve and Machines for Washing Using This Valve.xe2x80x9d In such systems, a specialty mixing valve is required that includes a thermostat placed in proximity to a thinned portion of an exterior wall of the valve to sense the water temperature therein. When the temperature of the water flowing through the valve increases above or drops below the set point of the thermostat, an internal switch closes or opens. In the system of the ""194 patent, this thermostat is used in line with the timer control circuit to hold off the timed closure of the cold water solenoid until the hot water flowing through the valve increases to its assumed or expected temperature. Specifically, the system of the ""194 patent prevents the timer control circuit from opening the cold water valve until and unless the hot water has reached the temperature set point of the switch. Indeed, for the one minute fill cycle example discussed above where the cold water solenoid is energized 30 seconds into the fill cycle, if the hot water never reaches the temperature set point of the thermostat, the cold water valve will be prevented from turning on during its 30 second timed cycle.
Unfortunately, while such systems address the problem of cool water in the hot water pipe during the initial period of a fill cycle, their operation is still fundamentally governed by the timer control circuit. As these systems cannot adjust for temperature excursions on the outside of the normally anticipated temperature limits. Therefore, such systems are not acceptable in view of the tighter energy usage requirements and in view of the potential damage to delicate fabrics. Specifically, systems such as that described in the ""194 patent cannot use temperature to directly control the turning on or off of either of the water valves. This control resides exclusively with the timer control circuit.
As such, if a user were to purposefully or inadvertently set the water heater temperature to an extremely high temperature, the system of the ""194 patent would allow this extremely high temperature water to flow into the wash tub for the full time period set by the timer control circuit. However, even though the thermostat of the ""194 patent would sense this very high temperature and close its electrical contact, the timer would continue to allow only the hot water to flow into the wash tub until the timed cycle for cold water flow had arrived. The result would be a washtub water temperature which is too high. Such a high temperature in the washtub may damage delicate fabrics, such as silk, and will exceed the energy utilization requirements for the appliance. Similarly, if the cold water input is much colder than expected, the hot water control valve still would not be turned on until the timer times out its predetermined period of time.
In other words, in systems such as that described in the ""194 patent, the wash tub water temperature is still a function of timed opening and closing of the hot and cold water temperature valves, regardless of the actual sensed temperatures. Therefore, these timed water temperature mixing periods cannot guarantee appropriate washtub water temperatures. As a result, delicate fabrics may be damaged due to over-temperatures, excessive energy may be wasted, and clothes may not be cleaned due to under-temperatures.
Another drawback of such systems is the requirement for the specialty mixing valve that includes the temperature elements integrated therein. The cost of these valves is much greater than the typical mixing valves, thus driving up the cost of the appliance. Further, since most manufactures produce both simple and more sophisticated appliances in their lines, the manufacture would have to either stock two different types of mixing valves, or use the more expensive specialty valve in the simpler models even though the temperature sensing functionality is not used. In the highly cost competitive consumer appliance industry, such additional costs cannot be justified.
There exists, therefore, a need in the art for a water temperature control system that allows for temperature corrected mixing hot and cold water inputs.
In view of the above, the invention provides a new and improved hot and cold water mixing valve that overcomes these and other problems existing in the appliance art. More specifically, the present invention provides a new and improved adapter that may be used with a conventional hot and cold water mixing valve. The adapter includes hot and/or cold temperature sensing and control circuits that automatically control the temperature of the water flowing through the valve. This control circuit operates directly to control the opening and closing of an opposite temperature control valve to minimize the water temperature excursion beyond the set point of the temperature sensing elements of the improved valve of the present invention.
In one embodiment, the invention is a device that is attached to a hot and cold water mixing valve for use in the laundry industry. A thermal acting switch is insert molded or placed into a pocket of an outlet for hose connections that are attached to the water valve by various methods. As water flows through the valve, the thermal switch senses the water temperature and closes at its predetermined temperature. A control circuit is included such that actuation of the switch provides voltage to operate the electric coil of a valve operator controlling the input of water of an opposite temperature. This valve operator then allows water of an opposite temperature to flow and mix with the initial water and change the temperature of the outlet water. Depending of the type of thermal acting switch provided, the present invention can be used to lower the output water temperature or raise the output water temperature or both. The outlet is constructed to hold a high temperature limit switch, a cold temperature limit switch, or both at the same time. The speed at which the thermal acting device activates can be sensitized or desensitized in the present invention by controlling the thickness of the wall between the switch and the water flow, by selecting specific properties of the material, or by the switch set points themselves. The outlet flow may also be controlled in one embodiment of the present invention through the provision of a flow control element therein.
Preferably, an embodiment of the invention utilizes thermal switches to control upper and/or lower temperature limits in a manner that requires no additional electronics external to the valve itself. That is, the valve of the present invention provides a self-contained high temperature limit on the water valve itself and/or self-contained low temperature limit on the water valve. As such, the more stringent energy standards becoming effective in 2004 and 2007 may be met by minimizing usage of hot water during wash cycles. Further, the washability of clothes during cold water washes is also improved by controlling the minimum water temperature during such washes. In an embodiment utilizing a spin-on or screw-on inlet, an optional flow control may be provided to provide maximum flow and temperature control fully contained within the valve of the present invention. Alternatively, such flow control may be provided by proper sizing of fixed orifices in the valve adapter body. However, embodiments of the present invention that utilize an optional flow control in the inlet allow for rapid accommodation of customer requested changes in the flow rate by simply replacing the flow control element.
In one embodiment of the present invention, the high temperature thermal switch is wired in series with the cold water inlet solenoid control coil. In this way, when the high temperature switch senses that the water temperature is above the set point temperature of the switch, the switch closes. This activates the cold water input valve control solenoid to allow the flow of cold water into the mixing valve. When the sensed output temperature of the water drops below the temperature at which the high temperature thermal switch resets, electric power to the cold water solenoid control valve is shut off, which closes the cold water input to the mixing valve. This process continues until the desired amount of water in the wash tub is reached.
The low temperature thermal switch is wired in series with the hot water input valve control solenoid such that when the switch senses that the water temperature is below the set point of the thermal switch, the switch closes, activating the hot water input solenoid control valve. This allows the flow of hot water into the mixing valve to raise the temperature of the water flowing through the outlet. Once the sensed temperature of this outlet water rises above the reset temperature of the low temperature thermal switch, the switch opens, thereby deactivating the hot water valve control solenoid to stop the flow of hot water into the temperature mixing valve. Depending on the application, embodiments of the valves of the present invention may include either or both of the temperature sensing switches. Indeed, embodiments of the present invention provide different orientations of these thermal switches, both in-line and perpendicular to the outlet water flow.
In one embodiment of the present invention, an adapter is provided for use with a mixing valve having hot and cold fluid inlets, a mixing body, and an outlet, the mixing valve further having electrically controlled valves governing the flow of fluid into each of the hot and cold fluid inlets. The adapter comprises a flow body having an adapter inlet adapted to be attached to the outlet of the mixing valve, an adapter outlet, and a flow channel. Preferably, the flow body also forms at least one sensor pocket having an interior temperature sensing surface positioned in thermal communication with the flow channel. The adapter also includes a thermal sensing switch positioned in the sensor pocket to sense a temperature of the interior temperature sensing surface. In one embodiment, the sensor pocket is positioned along a length of the flow channel. Alternatively, the flow body defining a sensing chamber adjacent the adapter inlet, and the sensor pocket is positioned perpendicular to a length of the flow channel. In this embodiment, the interior temperature sensing surface is positioned in thermal communication with the sensing chamber. Preferably, the adapter inlet is further adapted to receive a flow control element. In this embodiment, the adapter further includes a flow control element positioned in the adapter inlet.
In one embodiment, the thermal sensing switch is a normally open switch that closes upon sensing a temperature greater than a predetermined threshold. Each electrically controlled valve of the mixing valve includes a solenoid control coil having a line and a neutral terminal, and each side of the normally open switch is electrically coupled to the line terminal of each of the solenoid control coils. Alternatively, the thermal sensing switch is a normally open switch that closes upon sensing a temperature less than a predetermined threshold. In this embodiment each side of the normally open switch is electrically coupled to the line terminal of each of the solenoid control coils. Preferably, the thermal sensing switch is removably positioned in the sensor pocket. Alternatively, the thermal sensing switch is insert molded into the sensor pocket.
In an embodiment, the flow body further comprises a second sensor pocket having an interior temperature sensing surface positioned in thermal communication with the flow channel, and a second thermal sensing switch positioned in the second sensor pocket to sense a temperature of the interior temperature sensing surface of the second sensor pocket. In this embodiment when each electrically controlled valve of the mixing valve includes a solenoid control coil having a line and a neutral terminal, each thermal sensing switch is electrically coupled between the line terminals of each of the solenoid control coils. In any embodiment, a thickness of the flow body between the interior temperature sensing surface and the flow channel is selected to provide a predetermined thermal transfer rate. Also, a material property of the flow body between the interior temperature sensing surface and the flow channel is selected to provide a predetermined thermal transfer rate. In one embodiment the flow body is molded plastic.
In a further embodiment of the present invention, an automatic temperature regulating mixing valve is provided. Such an automatic temperature regulating mixing valve comprises a mixing valve body having hot and cold fluid inlets, and an outlet. The mixing valve body further has electrically controlled valves governing the flow of fluid into each of the hot and cold fluid inlets. Each of these electrically controlled valves has a line input. The automatic temperature regulating mixing valve also includes an adapter having a flow body including an adapter inlet attached to the outlet of the mixing valve, an adapter outlet, and a flow channel. The flow body forms at least one sensor pocket having an interior temperature sensing surface positioned in thermal communication with the flow channel. The automatic temperature regulating mixing valve also includes a thermal sensing switch positioned in the sensor pocket to sense a temperature of the interior temperature sensing surface. The thermal sensing switch is electrically coupled between the line inputs of each of the electrically controlled valves. Preferably, the flow body further comprises a second sensor pocket having an interior temperature sensing surface positioned in thermal communication with the flow channel, and a second thermal sensing switch positioned in the second sensor pocket to sense a temperature of the interior temperature sensing surface of the second sensor pocket.
A further embodiment of the present invention provides a method of providing automatic temperature regulation for a fluid mixing valve having hot and cold fluid inlets, a mixing body, and an outlet, the mixing valve further having electrically controlled valves governing the flow of fluid into each of the hot and cold fluid inlets. This method comprises the step of providing a flow body having an adapter inlet, an adapter outlet, and a flow channel, the flow body forming at least one sensor pocket having an interior temperature sensing surface positioned in thermal communication with the flow channel. The method also includes the steps of placing a thermal sensing switch in the sensor pocket to sense a temperature of the interior temperature sensing surface, attaching the adapter inlet to the outlet of the mixing valve, and electrically coupling the thermal sensing switch between a line input of each of the electrically controlled valves.
Preferably, the step of attaching the adapter inlet to the outlet of the mixing valve comprises the step of spin welding the adapter inlet to the outlet of the mixing valve. Additionally, the step of placing a thermal sensing switch in the at least one sensor pocket may comprise the step of removably placing a thermal sensing switch in the at least one sensor pocket. Alternatively, the step of placing a thermal sensing switch in the at least one sensor pocket comprises the step of insert molding a thermal sensing switch in the at least one sensor pocket. In one embodiment, the method further comprises the step of controlling a thermal response rate of the thermal sensing switch. Preferably, the step of controlling a thermal response rate of the thermal sensing switch comprises the step of controlling a thickness of the flow body between the interior temperature sensing surface and the flow channel. Further, the step of controlling a thermal response rate of the thermal sensing switch may comprise the step of selecting a material property of the flow body between the interior temperature sensing surface and the flow channel. Further, the step of controlling a thermal response rate of the thermal sensing switch may comprise the step of selecting alternate upper and/or lower switch limit settings. Still further, the step of controlling a thermal response rate of the thermal sensing switch may comprise the step of selecting alternate switch differentials, which is the number of degrees between opening and closing of the switch.
In one embodiment the step of providing a flow body comprises the step of providing a flow body forming two sensor pockets. Further, the step of placing a thermal sensing switch in the sensor pocket comprises the step of placing a thermal sensing switch in each of the two sensor pockets. In such an embodiment, the step of electrically coupling the thermal sensing switch between a line input of each of the electrically controlled valves comprises the steps of electrically coupling each of the thermal sensing switches between the line input of each of the electrically controlled valves.